[llvm] [SPARC][IAS] Make Is64Bit imply FeatureV9 in the assembler (PR #143232)

[via llvm-commits]

Rot127 wrote:

> Pinging @Rot127 too, does this help?

Yes, very. Although I would say `HasV9` should imply `Is64Bit`.
But this is probably not how the definitions are written and I can add a workaround for our very specific use case.

In any case, thanks for the fix!

https://github.com/llvm/llvm-project/pull/143232